The present invention relates to a resin vessel conveying system, and in particular, to a resin vessel conveying system of so-called neck conveyance type in which the conveyance is referenced to a flange formed around the neck of a resin vessel.
PET bottles formed of a resin are recently extensively used as a vessel in which a liquid content is filled. Such a resin vessel is of a light weight and very unstable, and this makes it difficult for the vessel to be rapidly conveyed on a common conveyor. The neck conveyance is therefore adopted, in which the conveyance takes place while supporting the lower surface of a flange formed around the neck of the vessel from below or while gripping the neck with an unlockable gripper to suspend the vessel.
Since the neck conveyance is based on the elevation of the flange formed around the neck of the vessel, it dispenses with the need for adjusting the elevation of vessel processors, conveyors or conveying wheels when applied to vessels of differing sizes, providing an advantage of universal use.
In a vessel conveying system in which vessels are continuously conveyed and processed, in the event of a failure or outage of a processor, if the vessels are left to stay in the processor for a prolonged length of time, the heat or the atmosphere in the processor may cause a deformation or a modification in quality of the vessels, which therefore must be cleared from the processor. Accordingly, a rejector or rejectors are usually provided along a vessel conveying line to allow the vessels to be cleared in such event.
An arrangement is known for use in a vessel conveying system of neck conveyance type which allows the gripper to be opened to release a vessel at a reject position in the course of a conveying path so that the vessel can be lowered onto a rotary table to be discharged (see Japanese Patent Publication No. 52,256/1981). This known arrangement suffers from inability to accommodate for vessels of varying sizes without the adjustment of the conveyor elevation when the vessels are directly lowered onto a conveyor or a rotary table, and thus is inapplicable to a vessel conveying system which deals with vessels of varying sizes.
The present inventor has proposed a vessel conveying system of neck conveyance type which is made applicable to vessels of varying sizes by allowing vessels to be handed over while their necks are gripped or supported when vessels are to be rejected from a conveying path, and which is the subject matter of an earlier Japanese Patent Application No. 119,935/2,000.
In the disclosed vessel conveying system of this Application, there is provided a vessel processor including a revolving body carrying a plurality of resilient gripper means disposed at a given circumferential interval around the outer periphery of the body and each operable to grip a vessel resiliently. A reject mechanism is disposed at a reject position around the vessel processor and comprises an unlockable gripper means disposed at a given circumferential interval adjacent to the outer periphery of a revolving body. The unlockable gripper means can be opened or closed to release or grip a vessel. When a vessel is to be rejected, the unlockable gripper means is closed as the vessel to be rejected reaches the reject position, thereby gripping that vessel and taking it out from the resilient gripper means on the vessel processor. The vessel which is taken out from the resilient gripper means is handed over to guide means (discharge chute) formed by a pair of parallel members to be discharged.
A vessel conveying system which is provided with a rejector as mentioned above is known as a resin vessel processing line, for example, including a rinser which rinses a resin vessel such as PET bottle in a sterile chamber and dries it with a drier before delivering it from the sterile chamber to a subsequent step such as a filler. In the operation of such processing line, the stream of dry air is not interrupted in order to prevent a pressure balance in the chamber from being distributed if a machine trouble occurs to stop the movement. If the machine should stay at rest for a long time interval, a vessel or vessels which are introduced into the processor such as the drier would be subject to the heat therein and become deformed. Thus, there is a need for the rejector to clear vessels which lie in a given zone on the conveying path to the outside in a consecutive manner if the machine stops over a given time interval.
However, if the line stop continues for an increased length of time, not only the barrel having a reduced wall thickness, but also the neck of the resin vessel which is utilized for the neck conveyance may be largely deformed. If the neck is largely deformed, a vessel gripper such as the unlockable gripper means will be unable to grasp the vessel, thus preventing a discharge of the vessel by the rejector. A vessel which cannot be rejected would continue to be conveyed on the normal line, and thus a manual intervention is required to remove the vessel by stopping the machine.
Accordingly, it is an object of the invention to provide a resin vessel conveying system including a reject arm capable of positively discharging a vessel, which cannot be discharged by reject means that is designed to grip and discharge a vessel, out of a conveying path.
Such object is accomplished in accordance with claim 1 by providing a resin vessel conveying system comprising a rotary conveying means including resilient gripper means disposed at an equal circumferential interval thereon and each operable to resiliently grip a vessel to convey it by engaging the latter above or below a flange formed thereon, and a rotary reject means including unlockable gripper means disposed at an equal circumferential interval thereon and each operable to open and close to grip and release a resin vessel, wherein a reject arm which is movable to and from a conveying path of the resin vessels is arranged downstream of the reject means on the conveying path, the reject arm being responsive to a reject signal to take out a resin vessel, which the reject means failed to take out of the rotary conveying means, out of the conveying path.
When a resin vessel is to be rejected, it is normally removed by the rotary reject means which grips the resin vessel. However, it is possible that the resin vessel may be deformed to a degree that it cannot be gripped by the unlockable gripper means of the rotary reject means, and such defective vessel would be carried past the reject position downstream while it is retained by the resilient gripper means of the rotary conveying means. With the resin vessel conveying system according to the invention, the reject arm arranged downstream of the reject position operates in such instance to positively discharge the vessel which the rotary reject means failed to grasp.
It will be appreciated that if the reject arm is simply moved into the conveying path, it would interfere with a vessel retained by the resilient gripper means of the rotary conveying means. Accordingly, such an interference is avoided in accordance with claim 2 by causing the reject arm to project into a space in the conveying path which is created by the operation of the reject means to take out the resin vessel.